Metal coating composition



Patented Aug. 10, 1943 UNITED METAL COATING COMPOSITION George M. Black, Cleveland Heights, Ohio No Drawing. Application March 21, 1940,

Serial No. 325,187

12 Claims.

My invention relates to a composition of 'matter, and more particularly to a coating composition containing a chromium soap. My invention.

formed of a ferrous base metal, it is the practice to first thoroughly clean the metal. The cleaning is usually effected by treating the metallic article with analkali, washing with hot water. and then treating with an acid. The article is then rinsed in cold water, dried, and the paint or composition is applied. When a fabricated article is to be coated, such as a ferrous base metal spring, it must be thoroughly cleaned before the paint or coating composition is applied, because in fabricating such articles it is necessary to utilize a mineral oil and unless-the oil is first thoroughly removed, paints or other compositions which have heretofore been applied will not adhere to the metal surface.

One of the principal objects of my invention'is to provide an improved composition of matter which may be applied to metallic articles, such as springs, without subjecting the article to the usual pretreating process and which when dried provides a durable film that will not chip or crack when subjected to expansion, percussion or contraction, and which is capable of preventing rust and corrosion of the base metal. The process of producing such springs may therefore be simplified and their production materially increased.

Another object is to provide an improved coating composition containing a chromium soap as a primary ingredient and which when dried is capable of producing a naturally black film having a hard, durable finish.

A further object is to provide an adherent coating composition containing a chromium soap and a solution or oil containing a mixture of resin and fatty acids.

Another object of my invention is to provide a metallic article, such as a spring, having a film thereon, one of the primary ingredients of which is a chromium soap.

A further object of my invention is to provide an improved process of applying a coating composition to metallic articles in which mineral oil vide an improved composition of matter comprising a chromium soap and an oil or solution containing resin and fatty acids, and a mineral oil.

In preparing my improved composition, I utilize a chromium soap, such as chromium oleate, chromium stearate, chromium naphthenate, or a mixture of two or more of such soaps. Preferably, I utilize the chromium soap of an unsaturated fatty acid, such as chromium oleate. Such soaps have corrosion resisting properties and expedite the drying of compositions in which they are present.

To provide a fiowable material. and to give hardness, finish and adherency to the final film, the chromium soap is dissolved in an oil or solution containing resin and fatty acids. To effect solution of the soap, it is necessary to mix the oil or solution with the soap and heat the mixture to a temperature varying from approximately 75 to 100 centigrade. The fatty acids in the oil or solution aid in dissolving the soap and preferably are higher fatty acids of the type which are present in or which may be derived from fats, vegetable oil or wood, such as pine. For instance, fatty acids, such as palmitic, oleic, lin'oleic, or stearic acid, or mixtures thereof, are suitable. The resin acids are those which are found in the ordinary natural resins, or in resin oils, such as abietic acid, pimaric acid ,and other resin acids, the composition of which are not definitely known. A

The resin and fatty acids may be present in the oil or solution in widely varying proportions.

is utilized during fabrication, such as springs,

and which have a film of the mineral oil thereon.

A still further object of my invention is to pro- The chromium soap, however, appears to be more soluble in the fatty acids than in the resin acids and consequently suflicient of the fatty acids should be present to provide a final composition having the desired amount of chromium soap. The resin acids on the other hand appear to increase the hardness and enhance the finish of the final film. I do not desire, however, to be limited to any particular theory as to the function of the particular acids. Better results, however, have beenobtained by utilizing a mixture of resin and fatty acids than when only resin acids or fatty acids are employed. r

An oil containing resin and fatty acids which is being sold commercially at the present time has proven very satisfactory for my purpose. This oil is known commercially as rosin oil or tall oil and is obtained from pine wood in pulp forming processes. The composition of the oil varies widely, depending upon the source and type of pine wood which is utilized and contains resin acids in proportions varying from 12% to 58%,

fatty acids in proportions ranging from 18% to 83%, and from 5% to 24% of sterols. A semirefined product is being-sold under the trade name of Liqro which contains from 40% to 50% resin acids, 35% to 45% fatty acids, and to sterols, and a refined double distilled product is being sold under the trade name of Indusol which contains from 43% to 47% fatty acids, 38% to 42% of resin acids, and 13% to 17% sterols.

In preparing my improved composition, the chromium soap is dissolved in the solution or oil containing the resin and fatty acids, suflicient heat being utilized to effect solution. When tall oil is utilized as a solvent for the chromium soap, the composition is in the form of a thick paste and a thinner must be added to provide a coating composition. If it is desired to provide a film by drying in air, a volatile solvent, such as naphtha, may be utilized. When it is desired to bake the composition upon the surface to be coated, it is necessary to utilize a diluent which does not volatilize at ordinary temperatures, such as kerosene or mineral oil, or a combination thereof. The relative proportions of the chromium soap and the solution or oil containing the resin and fatty acids, may vary widely. For instance, in such a composition, the chromium soap may constitute from approximately 8% to 60% of the composition. Since the chromium soap, however, is the most effective corrosion preventing component of the coating composition, it is preferably present in considerably greater proportions than 8%, such as in amounts ranging from 20% to While a composition may be provided which will dry in air, I preferably subject the coating to a baking operation to provide a more durable film. This is particularly true when it is applied to ferrous base articles, such as springs, which are subject to stresses in service.

To prevent too rapid drying during the baking operation, I perferably add a mineral oil in proportions sufficient to retard the drying tothe extent necessary for the production of a smooth film. Mineral oil, however, has the tendency to separate from chromium soaps. When a resin oil or solution containing resin and fatty acids isessary to vary the amount of oil containing the.

resin and fatty acids. In such compositions, the chromium soap may range from 8% to 60%, the oil containing the resin and fatty acids from 5% to 40%, and the mineral oil may be added in such proportions that a smooth film will be produced at the baking temperature, it being understood that as the quantity of mineral oil is increased beyond a predetermined amount, it is necessary either to increase the quantity'of oil containing the resin and-fatty acids or reduce the amount of chromium soap.

My improved composition may be applied to the article to be coated in any desired manner. For instance, it may be applied by brushing, dipping or sprayin the consistency being regulated for each process bythe addition of the appropriate amount of thinner.

As previously stated, my improved composition is especially adapted to be applied to fabricated articles, such as springs, because in fabricating such articles, a mineral oil is utilized which must be removed beforethe usual paint or coating composition is applied. In ordinary processes, it is necessary to utilize phosphoric acid to remove the oil and consequently the present process of preparing such springs is not only time consuming but expensive. When my improved composition is employed, however, it may be applied to the springs without any preliminary treatment, because an oil or solution containing the resin and fatty acids is miscible with mineral oil and since the chromium soaps have a naturally dark color, a dark coating is obtained without the ad Per cent Chromium oleate 10 Mineral oil j 20 Tall oil (Liqro) 20 Kerosene 48 The spring was-dipped in the composition and then passed directly to a drying oven where it was subjected to a temperature of approximately 300 to 600 Fahrenheit for thirty minutes. An adherent durable film was provided which did not chip or crack when subjected to expansion, percussion, or contraction and which was effective in preventing rust and corrosion.

My improved composition may be utilized as the final coating or as a base coating over which may be applied ordinary paints, enamels or varnishes.

To those skilled'in the art, many modifications of and widely differing embodiments and applications of my invention will suggest themselves without departing from the spirit and scope thereof. My disclosure and the description herein are purely illustrative and are not intended to be in any sense limiting.

What I claim is:

1. A composition of matter capable of adhering to a metal surface coated with a lubricant and of producing a hard durable film when apfrom said composition at said temperature to chip or crack when subjected to expansion, contraction or percussion.

2. A composition of matter capable of adher ing to metal gsu'rfaces coated with a lubricant and .of producing a hard durable film when applied to such surfaces and heated at a temperature of from300 to 600 Fahrenheit and comprising from 8%'to 60% of a chromium soap soap from the mineral oil.

and a sufficient amount of a rosin oil composed predominantly of resin acids and higher fatty acids to dissolve said soap, the higher fatty acids being of the type present in or derived from fats, vegetable oils and wood and said composition being free from inflammable ingredients which are volatile at normal temperatures and from ingredients which cause a film formed from said composition at said temperature to chi or crack when subjected to expansion, contraction or percussion.

3. A composition of matter capable of adhering to metal surfaces coated with a lubricant and of producing a hard durable film when applied to such surfaces and heatedsat a temperature of from 300 to'600 Fahrenheit and comprising from 20% to 35% of a chromium soap and a sufficient amount of an oil composed predominantly of resin acids and higher fatty acids'to' dissolve said soap, said fatty acid being of the type present in or derived from vegetable oils, fats and wood and said composition being free from inflammable ingredients which are volatile at normal temperatures and from ingredients which cause a film formed from said composition at said temperature to chip or crack when subjected to expansion, contraction or percussion. v

4. A coating composition capableof adhering to metal surfaces coated with a lubricant and of producing a hard durable film when applied to such surfaces and heated at a temperature of from 300 to 600Fahrenheit and comprising from 20% to of a chromium soap, a sufiicientamount of tall oil to dissolve said soap and a diluent, said composition being free from inflammable ingredients which are volatile at normal temperatures and from ingredients which cause a film formed from said composition at said temperature to chip or crack when subjected to expansion, contraction or percussion.

' 5. A coating composition capable of adhering composition, said composition being free from tard the drying of the composition sufficiently to provide a smooth film when the composition is applied as a coating and subjected to heat. and the oil containing resin and fatty acids being present in suflicient proportions to dissolve said soa and prevent'separation of the chromium 7. A coating composition capable of adhering to metal surfaces coated with a lubricant and of producing a hard durable film when applied to said surface and heated at a temperature of 300 to 600 Fahrenheit and comprising at least 8% of a chronium soap, 5% to 40% of tall oil, and a mineral oil which does not volatilize at normal temperatures in sufllcient proportion to retard the drying of the composition sufficiently to provide a. smooth film when the composition is applied and subjected to heat, said tall oil being present in suflicient proportion to prevent separation of the chromium soap from the mineral oil and said composition being free from inflammable ingredients which are volatile at normal temperatures and from ingredients which fihn thereon which does not chip or crack when subjected to expansion, contraction or percussion, said film consisting essentially of a chromium soap and the residual portion resulting from heating a mixture of resin acids and higher fatty acids to' a temperature of 300- to 600 Fahrenheit in the presence of said soap for suflicient time to produce said film, said fatty acids being of -'the type present in or derived from fats, vege-' table oil and wood and the residual portion of said resin and fatty acids being present in sufficient proportion to bind said chromium soap to the metallic article when heat is applied at said temperature.

9. A metallic spring formed of a ferrousv base metal having a hard durable film thereon which does not chip or crack when subjected to expansion, contraction or percussion and consisting essentially of a chromium soap and the residual portion resulting from heating a mixture of resin acids and higher fatty acids at a temperature of 300 to 600 Fahrenheit in the presence of said soap for sufficient time to produce said film, the higher fatty acids being of the type present in or derived from fats, vegetable oils and wood and the residual-portionof said resin and fatty acid being present in suiilcient proportion to bind said soap to the metallic article when heat is applied at said temperature and said film being freefrom ingredients which chip or crack when subjected to expansion, contraction or percussion.

10. A ferrous base metal spring having a hard durable film thereon consisting essentially of a portion to bind said soap to the metallic article 'when heat is applied at said temperature, and

said coating being free from ingredients which chip or crack when subjected to expansion, contraction or percussion.

11. A composition'of matter capable of adherins to metal surfaces coated with a lubricant and of producing a hard durable film when applied' to metal surfaces and heated at a temperature of 300 to 600 Fahrenheit and comprising from 8% to 60% of a chromium soap dissolved in tall oil, said composition being free from inflammable ingredients which are volatile at normal temperatures and from ingredients which are volatile at normal temperatures and from ingredthe metal bythe residual portion of tall oil which ients which chip or crack when a fllm formed has been heated at a temperature of 300 to 600 from said composition is subjected to expansion, Fahrenheit in the presence of said soap for sufcontraction or percussion. ficient time to produce said film and being free 12. A metallic articiehaving a hard durable 5 from ingredients which chip or crack when subfilm thereon, said film comprising from 8% to jected to expansion, contraction or percussion. 60% of a chromium soap adherently united to GEORGE M. BLACK. 7 

